The objective of the proposed program is the development and application of two new physical methods for the study of molecules and systems of biological importance. New physical methods include: a) X-ray diffraction using a synchrotron radiation source and b) perturbed angular correlation of gamma-radiation (PAC). These techniques will be applied to the study of diffuse diffraction from the membranes of myelin, the characterization of phospholipid vesicles, anomalous X-ray scattering effects, the structure of heart muscle, the structural integrity of lipid vesicles in vivo, and heme catabolism. The availability of X-radiation of extremely high intensity from the synchrotron radiation source available at the Stanford Synchrotron Radiation Project provides a unique opportunity to make structural measurements on active systems such as membrane and muscle. The perturbed angular correlation of gamma-radiation provides a labeling method for biological systems which yields information on molecular rotational correlation times, with a sensitivity comparable to that of radioactive tracer techniques. Since the gamma-rays have reasonable penetration distances, the method can be applied to the study of molecular rotation and conformational changes in vivo. This method will be applied to the study of the dynamics of several interesting biological processes. Results obtained thus far indicate that biological systems can be studied using the synchrotron source and the low-angle X-ray diffraction camera, with significant advantages over conventional X-ray generators in certain applications. The perturbed angular correlation techniques appears to provide information not available in other ways.